Hectograph blanket and method of preparing same



Oct. 28, 1941. w. HosKms. JR- 2,260,379

HECTOGRAPH. BLANKET AND METHOD OF PREPARING SAME 7 Filed March 6, 1939 Zz/z ZZz'avz 25,721

Patented Oct. 28, 1941 HECTOGRAPH BLANKET AND METHOD OF PREPARING SAME William Hoskins, Jr., La Grange, Ill.,' assignor to Ditto, Incorporated, Chicago, 111., a corporation of West Virginia Application March 6, 1939, Serial No. 260,012

3 Claims.

The invention relates to improved hectograph blankets which may be in the form of pads, bands or rolls, and to methcdsfor their preparation.

One embodiment of the invention is a cloth backed hectograph blanket in which the cloth backing is impregnated with 'a protein composition including a tanning agent which is present in such amount that it will diffuse into and react with the overlying hectograph duplicating composition, so that the lower portion of the duplicating composition is tanned and toughened to a greater extent than the portions more remote from the backing. In this manner there is provided a hectogra-ph blanket of improved toughness, resistance to wear and increased life.

Other objects and advantages of the invention will become apparent as the following detailed description progresses, reference being had to the accompanying drawing in which Fig. 1 is an enlarged cross-sectional view of one type of hectograph blanket embodying this invention.

Fig. 2 is a perspective view of a hectograph roll. a 4

Referring to the drawing, the reference character i denotes a gelatinous copy mass secured by means of a thin bonding layer 2 to a backing 3 which is impregnated with a composition containing suitable quantities of tanning agents, and coated on its outer surface with a protective lacquer 4.

In accordance with this invention the tanning agents in the backing 3 may suitably be any of the known tanning agents or protein precipitants such as formaldehyde, alum or the like, or of light sensitive tanning agents such as the chromates or dichromates. However, I prefer to use the aldehyde type tanning agents, particularly ning agent from the backing will not be too greatly retarded. In the case where the impre nating composition of the backing is itself ad- I hesive the intermediate bonding layer 2 may be eliminated. In such instances, however, the outer surface of the cloth backing should be covered with a non-adhesive lacquer 4.

The non-adhesive lacquer 4 may suitably be a cellulose ester lacquer, or some other coating material which will adhere to the backing and have little or no adherence to the gelatinous duplicating mass with which it is in contact when the hectograph blanket is in roll form. This protective lacquer is preferably used even when the impregnating composition of the backing which contains the tanning agent is of relatively nonadhesive character. However, when this impregnated composition is of such character that it will not adhere to the gelatinous duplicating formaldehyde, since such materials diffuse well into the gelatinous copy mass, being capable even of readily diifusing into the copy mass through the intermediate bonding layer 2.

The gelatinous copy mass maysuitably be any of the hectograph duplicating masses capable of being tanned by protein precipitants.- It may suitably be one of the glue and gelatin hectograph copying masses containing and tanned by tanning agents, but not to such an extent that it cannot be further reacted or tanned.

The intermediate bonding layer 2 may suitably be a thin layer of film formed from a drying oil such as linseed oil or the like, or may be a thin layer containing sulfonated oils such as shown in my Patent 2,098,662. Preferably the bonding layer is, made thin so that diffusion of the tanand react with the overlying hectograph duplimass when the blanket is in roll form, the protective lacquer 4 may be eliminated.

As a backing for the hectograph blanket there is contemplated paper or cloth. I have discovered, however, that backings made of cloth containing excess quantities of tanning agents such as formaldehyde and the like are superior to hectograph backings similarly made of paper, because of the higher retention of free aldehyde in the backing, and consequently better hardeningof the lower layers of the overlying gelatinous hectograph composition.

While not wishing to commit myself definitely to any theory regarding the cause of this superiority of cloth-backed hectograph blankets over paper-backed hectograph blankets in which the backing in each case contains an aldehyde rtanning agent, it is my belief that in paper there is present some material which slowly reacts with aldehyde to form non-tanning compounds. Over a period of time this material reacts with the excess aldehyde or reactive aldehyde combinations in the paper backing so as to materially reduce the amounts thereof. Cotton fabrics consisting of substantially pure cellulose are free from these aldehyde binding impurities and consequently retain the tanning properties undiminished for-a much longer time.

In accordance-with this invention the amount 'of tanning agent in the hectograph backing must be in sufficient quantity that it will diffuse into eating composition Preferably the tanning agent is present with the protein in the backing in excess of the amount required to completely vary for diflerent types of proteins and even for different glues, but it is a definite amount which can readily be determined for the particularproteinused. Perhaps the simplest manner of determining the preferred amount of tanning agent for the practice of the invention is to treat a sample of the protein to be used in the backing with progressively increasing amounts tanstill reactive combination with the glue or other protein, as the loss through evaporation is slight even when the very volatile formaldehyde has able tanning of the overlying hectograph'mass is accomplished when the aldehyde tanning agent is present in the backing in such quantities that when a portion of the backing is stored for two weeks and immersed in Schiils aldehyde reagent it will immediately show a strong red coloration indicating the presence of substantial amounts of free aldehyde. In the case where the backing is of cloth consisting of substantially pure cellulose impregnated with a protein containing an aldehyde tanning agent, an amount of tanning agent corresponding to 25% of that required for complete tanning of the protein is satisfactory,

To more clearly set iorth the practice in accordance with the invention, and to more specibeen used. It has been discovered that apprecifically point out the nature of the product and of 60 x 70 and or 1.75 yards per-pound is passed through a solution of 10% glue and 50% glycerine water mixture in such manner that each part of the cloth contacts the solution for to seconds at a temperature of F. Subsequently the cloth is immersed in a solution of 5% formaldehyde for two minutes or longer and dried. One surface of the backing so made is then coated with a bonding agent of sulfonated castor oil. and the gelatinous duplicating composition ap plied over it by means well known' to the art. The other side of the backing is lacquered with non-adhesive cellulose ester lacquer.

It is to be understood that the above example simply illustrates an embodiment of the invention which has given satisfactory results and is not intended to restrict the invention thereto.

While there have been shown and described certain embodiments of the invention, it is to be understood that it is capable of many modifications. Changes, therefore, may be made without departing from the spirit and scope of the in-" vention as described in the appended claims, in

which it is the intention to claim all novelty in- 1 herent in the invention as broadly as possible, in view of the prior art.

I claim:

1. A cloth-backed hectograph blanket, the

2. A cloth-backed hectograph blanket, the

backing comprising cotton cloth coated with a.

composition of glue and formaldehyde, the formaldehyde being present in excess of the amount required to completely tan the glue.

3. A hectograph blanket comprising a gelatinous copy mass secured by means of a thin bonding layer to a cotton cloth backing, said backing being impregnated with a composition comprising a protein containing an aldehyde tanning agent which is initially present in such amount that-the backing containing it will show a red coloration when immersed in Schifls aldehyde reagent. v

WILLIAM HOSKINS, Jn. 

